Bisphosphonate compounds are potent inhibitors of osteoclast activity, and are used clinically to treat bone-related conditions such as osteoporosis and Paget's disease of bone; and cancer-related conditions including multiple myeloma, and bone metastases from solid tumors. They generally have low oral bioavailability.
Patchy osteoporosis and bone marrow edema may result from osteoclast hyperactivity. Zoledronic acid is a potent inhibitor of bone resorption and osteoclast activity. Nitrogen containing bisphosphonates, such as zoledronic acid, also inhibit the mevalonate pathway in the osteoclast thereby interrupting normal osteoclast function.
Complex Regional Pain Syndrome (CRPS) is a debilitating condition characterized by severe, continuous, burning or throbbing pain often occurring in an extremity after injury or surgery. The excessive pain is accompanied by changes in skin color, temperature and/or swelling/edema. It is persistent, considered to be one of the most painful conditions a patient can experience (Tahmoush A J. Causalgia: redefinition as a clinical pain syndrome. Pain. 1981 April; 10(2):187-97), results in loss of physical function, and can lead to significant and sometimes permanent disability. Complex Regional Pain Syndrome (CRPS) is a rare condition that typically affects patients following a soft tissue, bone, or nerve injury. Patients with CRPS have to live with very severe and persistent pain, Classic analgesics offer only limited symptomatic relief, and currently no sufficiently effective treatments are available. For this reason, people with CRPS report lower quality of life scores than patients with most other chronic pain conditions. Patients frequently become socially isolated, lose their employment, and/or suffer from depression.
CRPS is a disease affecting less than 200,000 people with severe, persistent pain without sufficiently effective treatment options today. With no FDA- or EMA-approved drug treatments of CRPS today, there is a clear need for effective treatment options to address this significant unmet medical need.
One of the bisphosphonates, neridronate, is an innovative new medicine that may bring hope to CRPS patients.